Prior-art structures such as tents utilize some sort of a weight-bearing pole structure which, when assembled, forms a skeleton upon which the fabric covering is suspended. Most tents use bowed poles which place the cover under tension; the tension is usually provided by bending the support poles while suspending the tent from some type of an upstanding fabric sleeve or the like through which the poles are passed. Portable structures such as tents have existed for centuries and have always presented problems of various types.
One of the principal problems with portable structures is that associated with erecting them. In particular, the final set-up shape is completely unrecognizable when the components are laid out and the user must be familiar with an exacting set-up procedure. Segments of often different-length poles are connected and the longest passed through a specific sequence of fabric sleeves. The sleeves and tent cover form a confusing labyrinth and choosing the correct pole for the correct sleeve makes this an unforgiving process. The user also combats the tension of each pole during this process which becomes more difficult as more poles are added. After the last pole is passed through the fabric sleeves, all the poles are secured at both ends with either grommets and/or tie lines. The user must then manipulate this cumbersome bundle and secure it into its erected shape: it is only at this final step the structure becomes recognizable. And to complicate matters, the design of each tent is different from one structure to another so each must be learned separately.
Furthermore, if any one of the components are lost, torn, broken or misplaced, set-up of the structure could be impossible.
Ease of assembly becomes crucial in inclement or severe environments. In short, it is vital to be able to assemble a tent in the shortest possible time and with greatest ease. A user quite frequently cannot remove his mittens or gloves for prolonged periods for fear of cold, therefore a tent which cannot be assembled rapidly and preferably with the hands still encased in protective clothing is a significant liability. Attempts have been made to simplify the task of erecting portable structures. As exemplified by the "wedge" or "dome" tents, these attempts have resulted in impractical or still more complex structures:
Wedge structures rest on a generally rectangular base and are triangular with a connecting pole at the apex. This structure severely limits space near the user's head (headroom).
Dome structures provide increased headroom but waste floor space because they rest on unconventionally-shaped floors. Neither structure fits the user's sleeping bag(s) which are generally rectangular: hexagonal models create unusable sharp corners and square versions are far too wide. Further, both of these structures have apexes which are raised to ensure headroom throughout the tent's length. This compensation creates unused space through much of the central portion of the roof while creating a larger target for wind.
Attempts to simplify the task of erecting portable structures have also resulted in more expensive and heavier structures. Dome tents require added fabric: in addition to providing material for unusable floor and roof areas, the fabric must be cut to fit irregularly-shaped patterns resulting from overlapping support poles. Tenting material is wasted and extra workmanship to cut and sew numerous, irregular patterns raises costs. Further, dome structures require added support poles which are heavier than needed in-use to endure stresses of set-up and are therefore generally the costliest component of portable structures.
In most prior-art tents, the user is restricted from leaning against the assembled structure. The structural integrity of these tents is threatened by stressing a wall or pole by forcing them in a direction not designed to be tensioned. Under good conditions, the result may be a collapsed tent, however torn fabric walls and/or broken support poles may result in a ruined tent.
Some tents require the user to anchor the floor structure to the terrain through the use of stakes or the like during the assembly process. Stakes, or guy lines running to outlying stakes, suffer the obvious disadvantage of coming loose either by the tent working in the wind or by the user tripping over them during darkness. Such structures are often unsuitable for rocky or sandy terrain. Further, the orientation of these structures cannot be rapidly changed under varying weather conditions since the support element of the tent is violated when the anchoring devices are removed from the terrain.
Lastly, the poles in prior-art structures limit compactability of the tent. The span of the longest pole determines the packed length; attempts to shorten pole segments increases costs and set-up difficulties. 20 to 30-inch packed sizes are common despite backpack carrying frames being 14 to 15-inches wide. Therefore, the ends of the packed tent protrude to snag trees and bush during transport. Further, most structures pack into dense cylinders which are typically cumbersome and inconvenient to balance during transport.
Self-contained tension structures which eliminate support poles are known. Thus, the Saddle Tent of U.S. Pat. Nos. 3,990,463 and 3,960,161 is made of one flexible metal or plastic loop permanently attached to the structure's fabric. However, as the authors themselves disclaim: "the use of tie members stabilize the frame and holds it and the remainder of the structure upright which the frame alone cannot do." This is not a freestanding structure and the disadvantages of fastening the structure to the terrain to establish the support element of the structure have been described.
These consequences have prevented prior-art fabric tension structures from easily erecting and effectively gaining popularity.
Accordingly, several advantages of the present invention are: